Letter sorting machines



Jan. 23, 1962 H. OSBORN ETAL LETTER SORTING MACHINES Filed July 6, 1959 8 Sheets-Sheet I lNVE/V'IDR in, m y M (ZZZ BY 41%" 1%, ZMJ 94% J ATTORNEY Filed July 6, 1959 8 Sheets-Sheet 2 ATTORNEY Jan. 23, 1962 H. OSBORN ETAL 3,018,009

LETTER SORTING MACHINES Filed July 6, 1959 8 Sheets-Sheet 3 c0015 c0125 570/25 v, 57025 v, 1 V8 l c005 23 com; 570/25 v 570/?5 v ABCDEFGHJKLM Fig .3.

TUBE MA TR/X V3 22-+ III III I.

Vl/ENTOE ATTORNEY Jan. 23, 1962 OSBQRN T 3,018,009

LETTER SORTING MACHINES Filed July 6, 1959 8 Sheets-Sheet 4 INVENTOR Jar, gnu/1 A TTORNE Y Jan. 23, 1962 H. OSBORN ETAL LETTER SORTING MACHINES 8 Sheets-Sheet 5 Filed July 6, 1959 A 4 Q 4.. B 2 B X o 7 J w m C Q1 0 4 7 m/ Q Mi 2 .AM. rH H I V w 5 H: a 0 0 Q l .L 5 @E F B o w 9 Q I B 7 A TTORNEY Jan. 23, 1962 Filed July 6, 1959 H. OSBORN ETAL LETTER SORTING MACHINES I ll f H 1 8 Sheets-Sheet 6 Jan. 23, 1962 H. OSBORN ETAL 3,013,009

LETTER SORTING MACHINES Filed July 6, 1959 8 Sheets-Sheet 7 B ova/"am, 0%; 6 mm; (Jafuv;

ATTORNEYS Jan. 23, 1962 H. OSBORN ETAL LETTER SORTING MACHINES 8 Sheets-Sheet 8 Filed July 6, 1959 El Id Q x vv mm mm W m u m m\ mhwpm m w 9% w W m" w v T3 m a M .M T Q i f. w M, W E m mm w I4 m N: fi mm m fi Q 97d 6 cm m Q A TTOR/VEIK United States Patent Ofice dfilbfillb Patented Jan. 23, i952 3,018,009 LETTER SORTING MACHINES Howard Osborn and John Douglas Gould, Bristol, England, assignors to The Thrissell Engineering Company Limited, Bristol, England, a British company Filed July 6, 1959, Ser. No. 825,261 Claims priority, application Great Britain July 21, 1958 8 Claims. (Cl. 214-11) This invention concerns improvements in letter sorting machines.

In some of these machines a large number of compartments into which letters are to be sorted are arranged in a number of superimposed rows. At one end of these rows there is provided a number of letter conveying and diverting devices, whereby letters appropriate for each row are fed upwards towards said row and then diverted to a conveyor system associated with said row, whereby the letters are carried along over the tops of the compartments of such row and discharged into various compartments as determined by electronically controlled devices, which cause the letters to be discharged from the conveyor system into the proper compartment.

Beneath the superimposed rows of compartments above mentioned, there is a further conveyor which conveys letters from one end of the machine to the other. At the first said end of the machine there are arrangements for feeding letters from a stack or pile and transferring them to the said further conveyor, and during feeding the letters stop at a viewing position so that the operator, by pressing suitable keys, can determine to which compartment each letter is to be delivered. In the machine being described there are twelve keys to each hand.

Associated with each row is a timing device consisting of a continuously rotating drum having pins or the like, which can be displaced on receipt of a suitable electrical signal so that a displaced pin eventually operates a lever which causes a passing letter to be diverted into the conveyor system of said row and a similar arrangement associated with each compartment causes the letter to be delivered into the correct compartment along said row.

The letters are fed from the aforesaid pile one at a time by a device such as a suction device which transfers them to a feed roller system which feeds them down to the entry to the lowest conveyor, that is, the afore said further conveyor.

The present invention is concerned with improvements to a letter sorting machine of the kind generally outlined above namely, one having superimposed rows of compartments, conveyor systems therefor, a device for feeding letters from a pile, and controls for determining to which compartment a letter is to be delivered and such a machine will be termed a machine of the kind referred to.

It will be appreciated that the conveyors and diverting devices mentioned above move continuously at a uniform rate but the key-pressing is necessarily performed at a random rate since some addresses are poorly written or letters are curiously addressed, and sometimes a remote place only is given as the address and the operator in such case takes longer to think of the appropriate code. Therefore it is necessary that after key-pressing the entry of the letters to the conveyor systems feeding the rows and the compartments shall be synchronised with the rate of movement of the systems and also because the timing drum devices are associated with said systems. Moreover, the drum pins are displaced or set by a sloping cam which has to be projected between two neighbouring pins so that a pin can ride on the slope to be displaced and it is necessary to wait for a drum to be in a suitable position before the cam can be projected between two pins.

In machines as at present constructed the arrangements are substantially as follows:

The aforesaid further conveyor which is beneath the superimposed rows of compartments has a device known as a synchronising gate near its delivery end. When the keys are pressed the coded information is registered in a particular electronic tube (a cold cathode tube) of a matrix of such tubes. By matrix is meant an arrangement of tubes in horizontal lines and vertical rows, the pressing of one key selecting a line and the pressing of the other key selecting a row, so that the tube occupying the position where the said line and row cross one another is energised. Associated with this matrix is a system of twenty-four continuously rotating drums fixed on a common shaft, the main timing shaft, and provided with pins in the manner referred to above when describing the compartment timing devices. Each drum appertains to a particular key of the keyboard and the shaft rotates in synchronism with the conveyor systems of the compartment rows. The tube of a matrix is arranged to hold coded information imparted to it by the pressing of two keys for such time as is necessary for the main timing shaft to rotate from the angular position occupied at the instant of key-pressing until the drums are in pinsetting position, that is, when a pin is in a position to be operated on by an electro-magnet and the pin operating cam can pass between two successive pins. The first matrix is associated with a similar matrix, the tubes in this case being thyratrons, which actually operate the electro-magnets, one per drum, to set the pins. Pinsetting of the main timing drums is effected by an anode pulse applied to a thyratron by a switch closed by a cam rotating in synchronism with the main timing shaft. Pins thus caused to protrude from two drums of the twentyfour (one per key) eventually operate switches which open the synchronising gate and also perform other functions as described later. In this way, time is provided for a letter to pass along this conveyor to the synchronising gate and to wait there until the switches are operated so that, although the key-pressing is necessarily random, the letters enter the diverting and other conveying systems in synchronism with the movement of the parts of said systems.

Switch operation opens the gate and one switch causes grid feed to one grid of a two-grid thyratron in a third matrix While another switch causes grid feed to the other grid of said tube. The first said grid is one of a line while the second said grid is one of a row so that the pressing of the two keys for one letter has selected a particular thyratron from this third matrix. Associated with this third matrix is another timing shaft provided with a set of pin drums. Each of said tubes has a pinsetting electro-magnet in its anode circuit operative to set a pin in a rotatable drum associated with a particular diverter so as to choose the row to which a letter is to be delivered and a further magnet to set a pin in a timing drum, one to each compartment so as to select the compartment of the selected row to which a letter is to be delivered.

For reasons connected with the general design of the existing machine, a fourth matrix is provided to cause pin-setting for drums controlling the delivery of letters into compartments remote'from the synchronising gate.

It is desired to simplify this somewhat complex arrangement and this is done by providing a device to be described later and termed a twin waiting gate whereby a letter is delivered to the first conveyor of the series in proper timed relationship with the conveyor movements. This enables the first and second said matrices and the associated twenty-four pin-drum system and the synchronising gate to be dispensed with.

According to the invention there is provided a machine of the kind referred to comprising means for diverting successive letters fed to the machine to a different position of at least two possible positions, where a letter waits, a device operated in timed relationship with the conveyor movements to release the letter from said position to a conveyor of the conveyor system, and means operated in timed relationship with the conveyor movements to set a timing device (for example a pin in a timing drum) associated with the compartment to which said letter is to be delivered, the second said means being arranged to control said device which releases the letter to the conveyor so that release of the letter to the said conveyor is effected simultaneously with the setting of the timing device which device causes the discharge of the letter into said compartment.

Normally there are two possible positions to which the letters are delivered alternately. The diverting means may comprise a letter feeding device movable over said positions and letters may be located in said positions by delivery into chutes arranged at such positions.

The letter releasing device may comprise a movable flap at the bottom of a chute which closes the chute to retain the letter and moves to open the chute when the letter is to pass to the conveyor. The movement to open a chute may be effected under control of an electromagnet energised by current from an electronic tube through which current passes at a time determined by a further electronic tube whose current causes the setting of the said timing device. Flap movement to open a chute may be effected by a spring arranged to move a cam lever but controlled by a cam driven in timed relationship with the conveyors, said magnet operating to move a stop to permit the cam lever to move the flap, so that chute opening is effected in synchronism with the conveyor movements.

The apparatus recited in the preceding three paragraphs may be arranged to operate intermittently, that is, to stop at the end of a complete cycle during which one letter is fed to the conveyor system, and the cycles may be initiated by key-pressing by the machine operator which key-pressing determines, in the known manner, the compartment to which a letter is to be fed.

To determine which chute is to be opened there is provided a device movable in timed relationship with the letter diverting means (e.g. set into motion at the beginning of a cycle) and having an electro-magnetic arrangement whereby movement of the device causes a current to be generated during a brief period corresponding to a certain position of the diverting means, said generated current being arranged to control the passage of current through the tubes which energise the electromagnets controlling chute opening so that only the tube feeding the magnet of the chute in which a letter has been waiting passes current to energise said magnet and open the said chute.

The invention will be more fully described with reference to the accompanying drawings, in which:

FIGURE 1 is an elevation showing the arrangement of the various parts for feeding letters to the first conveyor, the view being of a diagrammatic nature and showing only fundamentals.

FIGURE 2 is a front view of a detail in FIGURE 1.

FIGURE 3 is a diagram of the basic scheme of the electronic control system.

FIGURE 4 is a diagram of devices for driving certain cams used in the machine.

FIGURE 5 is an enlarged view of a fragment of FIG- URE 1 showing a number of cams more clearly.

FIGURE 6 is a perspective view of a letter sorting machine of the kind referred to and embodying the invention.

FIGURE 7 is a front view of a timing device.

FIGURE 8 is a plan view of FIGURE 7 partly in section and with a part omitted.

FIGURE 9 is a side view of a detail of FIGURE 8.

FIGURE 10 is an external view of the timing device shown in FIGURE 8 in section, and shows its relationship to the compartments shown in FIGURE 6 and how a letter can be diverted into a compartment by the timing device.

FIGURE 11 is an enlarged view of part of FIGURE 1 showing the complete structure of parts, shown only diagrammatically in FIGURE 1, one part being broken away.

FIGURE 12 is a circuit diagram of certain electronic tubes and switching devices therefor, shown only diagrammatically in FIGURE 3.

Before describing the mechanism forming the subject of this invention a brief reference to FIGURE 6 is desirable as this shows the type of machine to which the invention is applied. At is a keyboard and when an operator presses two keys at once, one by each hand, a magnet which actuates a catch holding a single-revo-- lution clutch against movement is energised so that the clutch starts and makes one revolution and then stops. During this revolution a number of parts shown in FIG-- URE 1 are actuated as will now be described. These intermittent revolutions of the clutch will be referred to as cycles but as will be readily understood the time in-- terval between successive cycles is not necessarily constant as each cycle is started by the operator when he presses two keys, which represent a code.

Eventually the letters are fed into a conveyor 102 and this conveyor and several others above it constitute the conveyor systems characteristic of this kind of letter sorting machine.

Referring to FIGURE 1 letters are fed one at a time by any suitable device, such as a suction feed operating (once per cycle) on a pile of letters, to feed rollers 1 and belt 2 from which each letter drops into a chute 3. At the base of the chute are a pair of rotatable worms 4- which are set into operation at each cycle and on which a letter stands edgewise and is fed towards the right in FIGURE 1 when the worms rotate. The right-hand side of the chute is constituted by a pair of disc-like parts 5. A front view of one disc is shown in FIGURE 2. It will be seen, if the two views are compared, that the disc is rather like a single turn of a worm and the thin bent up piece 5A is adapted to move behind a letter and cause it to be brought to the front of the disc as the latter rotates. When a letter is fed to the worms it moves forwards until it touches the discs. Both worms and discs are driven from the one-revolution clutch referred to in more detail below with reference to FIGURE 4. The combined effect of the two devices is to bring a letter forwards to the front of the parts 4 in the following manner:

During the first cycle or revolution of the clutch a letter is fed to stand on the worms. During the next cycle the letter is brought to the front of the parts 5 and meanwhile the succeeding letter has been fed to stand on the worms. A third cycle causes a letter to drop off the worms 4 on to a movable support 8. The three successive positions thus occupied are indicated by the chain lines marked A, B and C. The worms 4 and discs 5 rotate very quickly and a letter dropping off the worms 4 on to the support 3 has its bottom part arrested by the stationary member 8 but its inertia causes its top part to be thrown forwards so that it assumes the position marked C.

6 is a window through which a letter standing on the support 8 can be read, the window being hinged at 7 so as to permit access to a letter if necessary. At each cycle the support 8 is swung about a pivot 9 and a letter standing on it falls to further feed rollers 10 which feed it down a further chute 11 having a hinged window 12, feed band 13 and a gate M. When the gate 14 is opened (once per cycle) a letter held in the gate passes to another feed roller system consisting of rollers 15 and belt 16 and this system delivers the letter to one of twin chutes 17A and 1713 as will be described later. A partition 18 separates the twin chutes and pivoted devices 19A and 12B cooperate with the partition to provide twin gates. When a gate is opened (once per cycle) to release a letter it passes to further feed rollers 29 and 21 and it will be noticed in FIGURE 1 that the path from rollers 26} to 21 is at an angle to the Vertical. The path is in fact the beginning of a curved path indicated by the two curved arrows and leading to the lowest conveyor 102 FIGURE 6 of the conveyor system, that is, the said further conveyor referred to in the beginning of this specification.

From the foregoing explanation it will be seen that during the interval between two cycles there are letters at each of the places A, B, C, chute 11, and either chute 17A or 17B and that at each cycle every letter moves onwards one stage and a new one is fed to position A. Successive letters occupy chute 17A and chute 17B alternately.

Parts of the mechanism so far described are ope-rated or controlled by several cams and a timing disc fixed on a cam shaft 22, FIGURES 1 and 4 described later. The cam shaft 22 is driven through the aforesaid one-revolution clutch which is indicated diagrammatically in FIG- URE 4 by a rectangle at 23. A suitable clutch is fully described and illustrated in the copending specification United States Serial No. 825,259, filed July 6, 1959. In FIGURE 4 the clutch 23 is shown as driven from a continuously rotating shaft 24 which runs in synchronism with the conveyor M2 and the rest of the conveyors forming the aforesaid conveyor system and the output shaft 25 of the clutch which shaft makes one revolution per cycle is coupled to the shaft 22 by 1:2 chain reduction gearing indicated at 26. Thus the cam shaft 22 rotates half a revolution each time the one-revolution clutch engages. The remaining parts illustrated are more conveniently referred to in the following description of the operation of the machine.

Referring now also to FIGURE 3 two sets of keys 34 and 35 are shown, the keys of each set running from A to M, one set being positioned for each hand of the operator. It is supposed in FIGURE 3 that the operator has pressed key F by his left hand and key C by his right hand and therefore in FIGURE 3 the appropriate wires are shown running from these two keys.

Associated with eac key of the board is an electronic tube and thus there is a bank of twelve tubes for each hand which are indicated by the two rectangles marked Code Store V1. In the arrangement diagrammatically illustrated in FIGURE 3 there are a large number of electronic tubes employed and so as to assist in understanding the arrangement a further view, FIGURE 12, is provided. The view shows three tubes V1, V2 and V3 associated with a left-hand key, marked 113, as will now be explained. The pressing of a left-hand key has selected the tube V1, FIGURE 12, in one Code Store V1, FIG- URE 3, and the pressing of a right-hand key selects a tube in the other Code Store V1, FIGURE 3. As explained later a tube thus selected (one from each Code Store V1) becomes operatively connected to a tube in a Code Store V2, FIGURE 3, one such store appertaining to a left-hand key and one to a right-hand key, as shown in FIGURE 3. In FIGURE 12 the tube from the Code Store V2 appertaining to a left-hand key is marked V2. The tubes in Code Store V1 and Code Store V2 are all cold-cathode tubes.

The said two tubes selected, one from each Code Store V2" in turn become operatively connected to a single tube in a Tube Matrix V3 which contains 144 tubes, the selected tub-es V2 each operating to control one grid of the single tube V3. In FIGURE 3 the said single tube is indicated by a circle in the matrix and it is shown in FIGURE 12 as V3. The tubes are all thyratrons.

FIGURE 12 also shows the ultimate connecting of the tubes V1, V2 and V3 to five other tubes V4 thru V8 which effect immediate control of the operation of the various mechanical parts controlled by the electronic devices. The tubes V4 and V5 are two-grid thyratrons, V6 and V7 are cold-cathode tubes, and V8 is a triode.

A right-hand key has an identical arrangement of the tubes V1 and V2 illustrated in FIGURE 12 and two lines marked 88 and 89 at the bottom of the figure and terminating in arrowheads show respectively a feed from the tube V1 appertaining to a right-hand key to the grid of tube V8 and a feed from the tube V2 appertaining to a right-hand key to the other grid of the tube V3, these tubes V8 and V3 operating in response only to combined lefthand and right-hand key movements. As there are twelve of each of the tubes V1, V2, for each hand this is indicated in FIGURE 12 by stems leading from some of the circuit lines and marked X 12 L.H. or X 12 RH. as the case may be. The 144 matrix tubes V3 are indicated in FIGURE 3 by X 144. When both keys have been pressed one tube V1 from each Code Store V1 has its trigger charged and the joint output from the two tubes, that from the tube V1 appertaining to a right-hand key coming up the line 88 on FIGURE 12, charges the grid of the tube V8 and current passes to energise a magnet coil 86, FIGURE 12, to release the catch of the onerevolution clutch and permit the clutch 23, FIGURE 4, to engage. On the shaft 25 are four cams 27, 28, 29 and 30, each of which engages a micro-switch not shown in FIGURE 3 but shown in FIGURE 12 at 41, 42, 43 and 44 respectively. As the shaft 25 performs its single revolution, cam 27 eventually operates its switch 41 to break the anode lead to both the tubes selected, one from each Code Store V1, while cam 28 has opened its switch 42 to allow the potential on the trigger of tube V2 to rise to firing value, but this rise must occur before the switch 41 opens, otherwise the code is lost. The code from the two tubes, one selected from each Code Store V1 is thus transferred to two corresponding tubes, one in each Code Store V2. The selected tubes in stores V2 are connected to the electronic tube matrix marked Tube Matrix V3 in FIGURE 3 in the following manner. It will be observed from that figure that key F is a line key, that is, all the tubes on the horizontal line joined by the wire originating at F are capable of being energised after key F has been depressed, while the line from C leads to a vertical row, all the tubes of which are capable of being energised after the key C is pressed. The tubes in the Tube Matrix V3 are, as above mentioned all two-grid thyratrons and a left-hand key will, as shown in FIGURE 12, cause feed to one grid and a right-hand key will cause feed, through line 89 to the second grid and thus only one tube of the matrix is made conducting, that is the tube at the intersection of F line and C row in FIGURE 3.

In the introduction to the specification it was explained that in machines of the kind being discussed a timing device is provided for each row of compartments to cause any letters destined for a particular row to be diverted to that row and that a similar device for each compartment of a row was also provided, the devices comprising rotating drums having pins capable of being displaced on receipt of an electrical signal so that a displaced pin can operate a lever to cause diversion of a letter. In practice pin displacement is caused by movement of the armature of an electro-magnet provided for each drum.

The anode feed of the tubes V3 is through a switch 46 operated by a cam 32 on the constant speed shaft 24 but the feed is subject to further control by a switch 45 operated by another cam 31 also on the constant speed shaft. In the anode lead of every tube V3 is a coil 87 of an electro-magnet 126, FIGURES 8 and 10, having an armature whose movement causes a pin to be set in a timing drum so as to cause a letter to be diverted. A drum of this kind, one to each row, operates to cause letter diversion to the appropriate row and a similar drum, one to each compartment then causes diversion to the proper compartment in such row. Since there are a lot of compartments to each row (24 in the machine shown) the row diversion drum is arranged so that when the drum for a given compartment in a given row has its pin set, the drum for the row has its pin set by the current which energises the coil 37 of the compartment drum, a similar coil being provided for the purpose. In FIGURE 3 this idea is shown simply by a number of compartments 144 and a selected compartment, that is, one whose diverter is to be operated is marked 144A. FIGURE 10, described later, shows the arrangement of a compartment and its associated diverter.

The cam 30 operates its micro-switch 44 to control the feed of the grids of the selected tube in the Tube Matrix V3 from the cathodes of V2 in the following manner. The switch 44 functions in a similar manner to that of the switch 41, that is, the grid of V3 to which one lead from switch 44 is connected is held at earth potential until the instant for transfer of the code from the two tubes in Cold Stores V2 to the single tube V3. The other grid of V3 fed from the line 89 is controlled in the same way by cam 30 and switch 44. Before this transfer instant the switch 45 is closed and the potential on the anode of V3 will be relatively low and the current drawn through the tube and coil 87 will not be sufficient to operate the pinsetting mechanism of the corresponding timing drums. At the transfer instant, the switch 45 will open and the potential on the coil will rise and the current through the coil increase to a level sufficient to operate the pinsetting mechanism. The code having been transferred as above described from V2 to V3, the cam 29 causes the switch 43 to open and break the anode circuits of all the V2 tubes including the selected two which represent the code.

When a selected tube in Tube Matrix V3 conducts as above described a connection from its cathode charges one of the grids in each of two further two-grid tubes V4 and V5. The tubes V4 and V5, see FIGURE 12, have coils 111 and 112 in their anode leads which constitute the windings of electro-magnets 77 and 82, FIGURES l and 11, which control the opening of the gates 19A and 19B in a manner described below.

Selection of which tube V4 or V5 is to fire is effected through further tubes V6 and V7 which operate to-charge the second grids of the tubes V4 and V5. Tubes V6 and V7 which, as aforesaid, are cold-cathode tubes, are themselves subject to control by a disc 36 which is fixed on the half-revolution shaft 22. This disc has a permanent magnet 90, see also FIGURE 1, fixed at one position in its rim and adjacent the periphery of the disc are two inductive coils 91 spaced at 180. As the disc only rotates half a revolution during each cycle only one coil 91 is influenced and each coil is in the trigger line of one or other of the'tubes V6 and V7 so the coil in which a current is induced charges its associated trigger and tube V6 or V7, as the case may be, conducts and charges the other grid of its corresponding tube V4 or V5. Another cam 32 on the continuously rotating shaft 24 eventually operates'the switch 46 and breaks the anode lead to the tubes in the Tube Matrix V3.

After the aforesaid magnet coil 111 or 112 has been energised to permit opening of gate 19A or 19B, as the case may be, the anode feed to tubes V4 and V5 is broken by a further micro-switch $7 operated by a cam 33 on the continuously rotating shaft 24.

Referring again to FIGURE 1 the cam-shaft 22 which, as will be understood from the foregoing, only rotates through 180 for one revolution of the clutch carries four cams as well as the timing disc 36. Two of these earns 37 and 38 jointly operate a lever 47 pivoted at 48. The lever has two rollers 49 and 50 and another lever 51 is fixed to it. A link 52 connects the lever 51 to a further lever 53 integral with a frame 153 carrying the rollers 15 and belt 16, the frame being pivoted at 54. Thus as the earns 37 and 38 rotate, the first half-revolution will swing the frame one Way and the next time the cam shaft makes a half-revolution the frame will be swung the other way and so each movement diverts a letter into chute 17A or into chute 17B as the case may be. Letters are admitted to the path between the rollers 15 and belt 16 from the gate 14 at about the time that the frame starts to swing andthe gate 14 is opened by another cam 39 on shaft 22 which. engages a roller 55 on a lever 56 pivoted at 57. The lower end of lever 56 is connected by a link 58 to a lever 59 pivoted at 60 and fixed to the left-hand member of the gate 14. Another roller 61 fixed to a lever 62 also pivoted at 57 and having an extension 63 engages a cam 40 and? operates the flap 8 through a link 64 and a lever 65 pivoted The devices 19A and 19B are operated through levers and links but as in FIGURE 1, which is to a small scale, the various members would overlap and obscure the view they are shown for convenience in FIGURE 1 by heavy lines.

The actual construction employed is shown in FIGURE 11. Referring also to FIGURE 11, part 19A is pivoted at 66 and movement of a lever 67 will cause it to swing on the pivot. Lever 67 is connected by a link 68 to a double-armed lever 69 pivoted at 70. A further link 71 connects the lever 69 to a lever 72 pivoted at 73 and having a roller 74 attached to it which engages a cam 75. The cam 75 is driven from the constant speed shaft 24 by chain gearing 83 and a pair of gear wheels 84, the drive giving a one to one ratio. Normally the lever 72 is held from movement by a stop exactly like the stop 76 illustrated but behind it. The stops are slidable on a support pin 92 and the stop appertaining to the lever 72 can be moved to release the lever by the movement of a pivoted lever 77A following the energis-ation of an electro-magnet 77. In FIGURE 11 the lever 77A is shown broken because if it is continued until it touches 76 it would appear to be attached to 76 whereas it is attached to a part like 76 but behind it. The other part 19B is operated in a similar manner by the lever 78, a long link 79, cam 85, on the same shaft as cam 75, cam roller 80 and lever 81, which is also pivoted at 73. In FIG- URE 1 the lever 81 is shown bent for clarity. Lever 81 is held against movement by the stop 76 but this can be moved, to permit the lever to swing on pivot 73, by the electro-rnagnet 82. The levers 72 and 81 are moved by the springs 93 to open the gates 19A and 19B when the stop 76, or its fellow, is withdrawn as described, so that the roller 74 or 80 can follow its cam 75 or to open a gate by the linkage shown.

The coils 111 or 112 of the magnets 77 and 82 respectively, are, as previously mentioned when describing FIG- URE 12, energised by the currents through tubes V4 and V5. The current from the chosen tube in the Tube Matrix V3, that is the tube selected by the keying, energises the coils of the corresponding magnets on the timing drums of the appropriate row and compartment, as for example coil 87 FIGURE 12 which is the coil of the electro-magnet 126, FIGURE 8, and also determines the instant of energisation of the magnet 77 or 82 which magnets control the gates and the opening of a gate 19A or 19B and therefore the letter is discharged to the conveyor system in proper timed relationship with movements of the conveyors of the conveyor system and thus the letter is eventually discharged into the correct compartment.

The operation will be better understood by assuming that the machine is actually running. In that case successive letters occupy the positions marked A, B and C in FIGURE 1, that is, as one letter moves into one position the next letter moves into the position vacated by the first. While a letter is in position C a preceding letter is in the chute 11 and the one preceding that in chute 11 is in either chute 17A or 17B. The letter preceding the one in chute 17A or 1713 has just been discharged into the conveyor system. Every time two coding keys are pressed all the letters move on one stage because key pressing starts the one-revolution clutch and other events take place as will now be explained.

The operator reads the address on the letter standing in position C while he presses keys for the coding of the preceding letter which, following the previous key pressing has dropped from position C to chute 11. If he has made a mistake in the coding of said preceding letter he can still see it through window 12 and can press a cancelling key whereby the letter is diverted to a special cancelled box. Diversion is effected in much the same way as sorting, merely by diverting improperly coded letters into a special compartment by a particular key manipulation.

Pressing one key alone is ineffective to operate anything. Key pressing charges the triggers of two selected tubes V1 and in consequence the tubes fire and the grid of tube V8 is charged and the tube fires and operates the coil 86, FIGURE 12, which releases the catch of the clutch 23, FIGURE 4, which forthwith starts to drive shaft 25 and, through the reduction gearing 26, the shaft 22. The gate 14 opens by cam operation from shaft 22 and the letter held in chute 11 passes into the feeder system 15, 16, which system is swung to and fro alternately at each cycle by cam operation to discharge the letter into the empty chute of chutes 17A and 17B, one chute of course already holding a letter.

The said key pressing has not only charged the triggers of tubes V1 but has also impressed a code on them since each key will have selected a particular tube in each Code Store V1.

In the single revolution of the shaft 25 the cam-operated switches previously mentioned in the description of FIGURE 12 transfer this code to equivalent tubes, one in each Code Store V2 and when this has been done break the anode circuits of all the tubes in stores V1, including of course the selected tubes V1. But before either transfer or anode circuit breaking has been done other cam-operated switches have transferred the code already existing in two tubes, one in each Code Store V2 (the result of the preceding keying operation) to a tube in the Tube Matrix V3 and then broken the anode circuits of tubes in stores V2 including of course the tubes V2 selected by said previous keying operation. In the same way the information just coded into tubes of the stores V2 is transferred by the next keying operation to a tube in the Tube Matrix V3 after the code already held in that matrix has been eliminated by said next keying operation.

One revolution of shaft 25 causes half a revolution of shaft 22, as previously explained, and during this movement one coil 91 will be energised by the passing magnet 90. This will cause the trigger of tube V6 or V7 to be charged and the corresponding tube will fire and thus the aforesaid second trigger of V4 or V5 will be charged and held charged.

Conduction in the selected tube in Tube Matrix V3 takes place when the switch 45, FIGURE 12, is opened by the cam 31 on the constant speed shaft 24 and the event is thus in synchronism with the conveyor movements.

Thus conduction through tube V3 will not only charge the first said triggers of V4 and V5 so that one of them, as selected by the coil 91 which has been energised at about that time, will fire and energise one of the magnets '77 or 32, according to which coil 91 has been energised, and thus cause one of the gates 19A or 1913 to open, but it will at the sarne time set the pins of row and compartment timing drums to the code (i.e. matrix position) of said tube V3.

The switch 87 operated by cam 33 breaks the anode circuit of tubes V4, V5 and V6, V7 as soon as they have fired. In this way the gate of one of the chutes 17A and 17B is opened at the precise instant for the letter to enter the conveyor system in synchronism with the conveyor movements and with pin setting of the appropriate timing drums. A twin gate arrangement such as has been described is essential when an operator is coding letters near to the maximum possible speed. Without the twin gates if one letter just missed its timed position the next one would be capable of catching it up and could go with it into the wrong compartment.

Referring now to FIGURE 6, the keyboard is indicated at 1% and the windows 6 and 12 of FIGURE 1 are also shown. The arrow 101 points to the position where the lower part of the mechanism shown in FIGURE 1 is situated, the point of the arrow being approximately on the position of the gates 19A and 193. The said first conveyor of the conveyor system is shown. at 102 and the line of arrows indicates the movement of letters along it and at the far end of the machine vertical arrows show the general upward movement and curved arrows indicate how selected letters are diverted into one or other of the five conveyors positioned above the rows 105 to 109 of boxes. These conveyors are obscured in the view by cover sheets but one of these is broken away to show a fragment of a roller conveyor system 110.

Letters to be sorted are stacked at 1031 and inside the casing 104 is a pneumatic letter feeder of known kind, some of the rollers of said feeder being shown at the top of FIGURE 1. All the conveyors are roller feeding devices and are only indicated schematically, further details being shown and described in the copending specification U.S. Serial No. 808,697, filed April 24, 1959.

In the description of FIGURE 3 it is explained that a coil in the anode lead of V3, that is the coil 87 in FIGURE 12, is energised to cause a pin to be set in a timing drum. Each compartment has one such drum and similar drums are provided for operating the devices which divert letters to one or other of the five conveyors. It will be seen then that the act of pressing two keys results in a pin setting operation for a row of compartments and another similar pin setting operation for a particular compartment along such row. These drums are convenient devices for this purpose but any other suitable timing device could be used. A timing drum for a compartment is shown in FIGURES 7, 8, and 10, and will now be described.

A shaft 121) driven in any convenient manner in the direction of the arrow on FIGURE 7 is supported in a long bush 121, fixed in a bearing 122. A drum 123 is fixed to the shaft 121) and has a number of pins 124 equally spaced around a circle concentric with the shaft axis. The pins are pushed in and out as described below and are held against accidental movement by coil springs 125 extending around the periphery of the drum. 126 is an electro-rnagnet, whose coil is the aforesaid coil 87 in the anode lead of V3 in FIGURE 12. The magnet has an armature 127 pivoted at 123 to a bracket 129 fixed to the bush 12 1. A flat spring 139 presses on the armature. In the full-line position FIGURE 8, the magnet is energised and the armature, which is bevelled at its operative end, see FIGURE 9, has engaged a pin and pushed it outwards as will be understood by comparing the pin engaging the armature in FIGURE 8 with a nearby pin. When current is cut off from the magnet coil the spring 130 returns the armature to the chain-line position FIG- URE 8. Movement of the armature to the operative position takes place at such time that the armature can be inserted between two neighbouring pins since V3 can only conduct sufficient to operate 126 at an instant in timed relationship with drum and conveyor movements as the conduction in V3 is determined by the cam 31, FIGURE 12, which rotates in synchronism with conveyor movements, so that the pin to be moved can ride up the armature bevel. It is partly for this reason that the synchronising gate referred to in the introduction was provided on existing machines and the gates 19A and 19B of the present machine are similarly necessary.

Eventually a pin 124 set in the manner described contacts at one end 131 of a lever pivoted at 132, the other end 133 of the lever being linked to a rod 134 which operates a bell crank 135 which is fixed at 136 to a rod 137 which operates a guide or diverter FIGURE 10. In FIGURE the drum and its associated parts are shown in full lines in the position they occupy at the back of the machine frame 114 and at the other side of the frame are the compmtme-nts 144 and roller conveyors as shown in FIGURE 6. A few compartments 144 are shown dotted in FIGURE 10 and above them are rollers marked 115 of a roller conveyor such as the one marked 11% in FIGURE 6. 116 is a diverter fixed to the rod 137 an when it istipped counterclockwise a letter instead of passing along the conveyor is deposited in a compartment, namely the one immediately at the back of the drum. Details of the conveyors and compartments may be seen in the copendingspecification U.S. Serial No. 808,697, filed April 24, 1959.

After a pin has operated the diverter it is pushed back to its normal position by a cam 139 shown in FIGURES 7 and 10. This cam slopes towards the pin path from the position where it first engages the pin to its upper end in FIGURES 7 and 10 so that the pin is gradually restored to its normal position and the slope can be followed from FIGURE 10.

What we claim as our invention-and desire to secure by Letters Patent is:

1. A letter sorting machine of the kind having superfimposed rows of compartments, conveyor systems therefor, a device for feeding letters from a pile and controls for determiningto which compartment a letter is to be delivered, said machine comprising means for diverting successive letters fed to the machine to a different position of at least two possible positions, where a letter waits, a device operated in timed relationship with the conveyor movements to release the letter from said position to a conveyor of the conveyor system, a timing device consisting of a movable member on a rotating drum, and means oper- .ated in timed relationship with the conveyor movements to set said timing device, the second said means being arranged to control said device which releases the letter to the conveyor so that release of the letter to the said conveyor is effected simultaneously with the setting of the timing device which device causes the discharge of the letter into said compartment.

2. A machine as claimed in claim 1 wherein said letter diverting means comprises a letter feeding device movable over said positions.

3. A machine as claimed in claim 1 wherein said positions are defined by chutes and the letter releasing device comprises a flap at the bottom of each of said chutes movable to open and close the associated chute and means for moving the flap to open the chute when a letter is to pass to the said conveyor of the conveyor systems.

4. A machine as claimed in claim 3 comprising for each flap a cam driven in timed relationship with the conveyor system, a cam lever coupled to said flap and having a follower engaging said cam and urged into contact therewith by a spring, a stop for preventing movement of said cam lever by the spring, an electro-magnet for shifting said stop to permit movement of the cam lever, an electronic tube for feeding current to the electro-magnet and a device for selecting which electro-magnet is to be energized, whereby the desired flap is moved to open its chute, so that chute opening is effected in synchronism with said conveyor movements.

5. A letter sorting machine as claimed in claim 1 comprising means for causing intermittent operation of the devices for feeding a letter from the pile and delivering it to the said conveyor of the conveyor systems whereby said devices start and stop at the end of a complete cycle during which one letter is fed to said conveyor, and a keyboard which is operated to start the cycle and to control the setting of the timing device associated with the compartment to which the letter is to be delivered.

6. A letter sorting machine as claimed in claim 4 wherein the device to select which electro-magnet is to be energised comprises an electro-magnetic generator having a rotatable magnet and coils disposed at equally spaced intervals around the axis on which the magnet rotates, and means for rotating the magnet at such speed as to pass one of said coils for each letter released to the said conveyor of the conveyor systems, whereby said one coil is energised and the said electronic tube is caused to feed current to the electro-magnet.

7. A letter sorting machine as claimed in claim 1 comprising a keyboard having duplex key sets, a bank of electronic tubes, each having a grid, for each set of keys and a line from each key of its set to the grid of a separate tube in its bank whereby key pressing charges a tube grid, and two tubes, one in each bank to jointly pass current, a further tube and an anode supply therefor, said tube having a grid connected to the said two tubes whereby said grid is charged, a magnet coil connected to said further tube to be energised by current therefrom, a singlerevolution clutch arranged to drive the devices for feeding letters from the pile, the means for diverting letters so fed, to said different positions, and the device which releases a letter to the said conveyor of the conveyor systems through a single cycle during which one letter is released to said conveyor, said clutch being set into operation by the said magnet coil when energised by current from the last said tube.

8. A letter sorting machine as claimed in claim 7 comprising two further banks of electronic tubes, each tube having a grid, switch operating cams driven by said clutch through one revolution per cycle and a switch operating cam driven continuously in timed relationship with the said conveyor movements, one of the first said cams operating to connect the cathodes of the said tubes in the first two banks to the grids of corresponding tubes in the said further banks, a second of the first said cams operating thereafter to break the anode leads to the said tubes in the first two banks, whereby said corresponding tubes are substituted for the said tubes in the first two banks, a matrix of two-grid electronic tubes arranged in lines and rows, each line and each row having a number of tubes equal in number to the number of tubes in a bank, a third of the first said cams operating to connect the grids of a line and row respectively of the matrix tubes to the cathodes of said corresponding tubes in the further banks whereby a single tube in the matrix has both grids charged, the continuously driven cam operating thereafter to cause anode feed to the anode of said single tube which thus starts to pass current in timed relationship with the said conveyor movements, said single tube operating to set the said timing device.

References Cited in the file of this patent UNITED STATES PATENTS 2,677,473 Piggott May 4, 1954 FOREIGN PATENTS 528,189 Great Britain Oct. 24, 1940 751,931 Great Britain July 4, 1956 

